Periplanone-B is the main component of the sex pheromone of female American cockroaches (Periplaneta americana) which are a type of harmful insect distributed worldwide. C. J. Persoons et al. were the first to separate this component and determine its plane configuration, and they reported that this component had a specific germacrene-type sesquiterpenoid configuration (C. J. Persoons et al., Tetrahedron Letters, 24, 2055 (1976)). According to Persoons et al., periplanone-B produces a very strong physiological effect; 1 picogram (1/100,000,000,000 gram) of this component attracts and sexually excites male American cockroaches. W. C. Still et al. synthesized a racemic material of periplanone-B and determined its relative configuration (W. C. Still, J. Am. Chem. Soc., 101, 2495 (1979)). K. Nakanishi et al. optically resolved the racemic material synthesized by Still et al. and determined the absolute configuration of periplanone-B by a spectroscopic method (K. Nakanishi et al., J. Am. Chem. Soc., 101, 2495 (1979)). S. N. Schreiber reported another method of synthesizing periplanone-B in J. Am. Chem. Soc., 106, 4038 (1984).
As has been described above, periplanone-B is a sex pheromone of American cockroaches and can be used to attract or trap male American cockroaches in a specific location. However, insects including American cockroaches produce only a small amount of sex pheromone, and extraction thereof is not practical. Therefore, development of a method which allows synthesis of periplanone-B on an industrial scale is desirable.
In the synthetic methods of Still et al. and Schreiber et al., the starting material is a racemic material (ethoxyethyl ether of (.+-.)-5-(hydroxymethyl)cyclohexenone in the former, and (.+-.)-4-isopropyl-2-cyclohexen-1-one) in the latter). Therefore, periplanone-B obtained as a final product in either method is only a racemic material. A starting material racemic material used in either method is very difficult to resolve optically, and requires a complex process therefor. In addition, these methods use oxy-Cope rearrangement, which cannot be performed on a large scale, in the formation of a 10-membered ring, which is a key reaction in the synthesis of periplanone-B. These methods are not, therefore, efficient. Moreover, these methods include many steps which require fine adjustment of reaction conditions, such as organometallic reactions or stereoelective reactions.